"Where the Colorado River falls from the snow-capped Rocky Mountains into the arid U.S. Southwest, lies Lake Powell."

'It extends upstream into Utah from Arizona's Glen Canyon Dam and provides water for Nevada, Arizona and California.

'But a severe drought in recent years, combined with the tapping of the lake's water at what many consider to be an unsustainable level, has reduced its levels to only about 42 percent of its capacity, according to the U.S. space agency NASA.

'The peak inflow to Lake Powell occurs in mid to late spring, as winter snow melts in the Rockies. But since 2012, snow and rainfall totals have been abnormally low as the region suffered persistent drought.'

'Lake Powell in the United States is seen in a combination of NASA satellite images taken in 1991 (L) and 2015 (R). Lake Powell on the Colorado River provides water for Nevada, Arizona and California. via Reuters/NASA/Handout'